| 摘要 |
A rotary cone drill bit for forming a borehole having a bit body with an upper end portion adapted for connection to a drill string. A number of support arms extend from the bit body. Each support arm has an exterior surface. A number of cutter cone assemblies equal to the number of support arms are mounted respectively on the support arms and project generally downwardly and inwardly with respect to an associated support arm. A ramp is formed on the exterior surface of the support arm and is inclined at an angle from a leading edge of the support arm toward a trailing edge of the support arm such that the ramp directs cuttings upward in the borehole. |
